1. Field of the Invention
The present invention relates to a drum of a washing machine and a method for manufacturing the same, and more particularly, to a drum of a washing machine and a method for manufacturing the same in which the drum is rigidly and easily manufactured.
2. Discussion of the Related Art
Generally, a washing machine is an apparatus to get clothes, bedclothes and the like (hereinafter referred to as ‘laundry’) clean through washing, rinsing, squeezing and drying cycles such that dirt that has stuck on the laundry received in a drum is removed by a chemical interaction of water and detergent fed to a tub.
FIG. 1 is a sectional view illustrating an inside of a washing machine according to the related art.
Referring to FIG. 1, the related art washing machine includes a cabinet 3 disposed above a base 2, a laundry entrance hole 4 formed at a front side of the cabinet 3, and a cabinet cover 6 to which a door 5 for opening and closing the laundry entrance hole 4 is rotatably connected. A control panel 7 for inputting operation cycles or time of the washing machine is disposed above the cabinet cover 6. A top plate 8 is disposed on an upper surface of the cabinet 3.
A tub 10 accommodating water mixed with detergent or clean water (hereinafter referred to as ‘washing water’) is shock-absorbably installed above the base 2.
The tub 10 is mounted on a damper 2a connected with the base 2 and is hung and connected to a spring 3a connected to both sides of the cabinet 3 to be shock-absorbably supported by the damper 2a and the springs 3a. 
The tub 10 is shaped in a horizontal laid cylinder, and includes an opening 11 formed at a rear of the entrance hole 4. A gasket 14 is installed at the opening 11. The gasket 14 is closely in contact with a rear surface of the door 4 when the door 5 is closed, to prevent washing water (w) from being leaked and laundry (m) from escaping.
The tub 10 also includes a water feed hole through which washing water is fed, a water drainage hole through which washing water is drained, and a driving motor 15 formed at a rear surface thereof, for rotating a drum 20 to be described later.
The driving motor 15 includes a stator fixed to the rear surface of the tub 10, a rotator encircling a circumference and rear surface of the stator, and a shaft fixed to the rotator, perforating the rear surface of the tub 10 and fixed to a rear surface of the drum 20.
Like the tub 10, the drum 20 is shaped in a laid cylinder such that a lower side thereof is dipped in washing water (w) in the tub 10. The drum 20 is rotatably disposed inside the tub 10 and has holes 21a, 23a through which washing water or air passes, and a lifter 21b for lifting and then dropping the laundry (m).
Meanwhile, a water feed unit for feeding water mixed with detergent or clean water to the inside of the tub 10 is connected to a water feed hole of the tub 10.
The water feed unit includes a feed valve 30 connected with an extension hose 30a, for adjusting water supply through the extension hose 30a, a feed hose 32 for guiding water that has passed through the feed valve 30, a detergent box 34 receiving detergent therein such that the detergent is mixed with the water guided by the feed hose 32, and a feed bellows tube 36 for guiding the washing water that has passed through the detergent box 34 to the feed hole of the tub 10.
In addition, a water drainage unit for draining washing water in the tub 10 to an outside of the washing machine is connected to a drainage hole of the tub 10.
The water drainage unit includes a drainage bellows tube 40 connected to the drainage hole of the tub 10 such that the washing water (w) inside the tub 10 is drained, a drainage pump 42 for pumping the washing water guided to the drainage bellows tube 40, and a drainage hose 44 connected to the drainage pump 42, for draining the washing water pumped by the drainage pump 42 to the outside of the washing machine.
Operation of the above washing machine will now be described with reference to the accompanying drawing.
First, as a user opens the door 5, loads laundry (m) into the inside of the drum 20, closes the door 5, and inputs instructions such as washing, rinsing, squeezing and the like, the washing machine operates according to the input instructions.
When the washing cycle is inputted, the feed valve 30 is turned on to feed water. The fed water passes through the detergent box to be mixed with detergent, is received in inner lower side of the tub 10, introduced into the inside of the drum 20 through the holes 21a, 23a of the drum 20 to soak the laundry.
When a predetermined amount of water is fed to the inside of the tub 10, the washing machine turns off the feed valve 30 and turns on the motor 15 to agitate the drum 20 in the left and right direction.
When the drum 20 is agitated in the left and right direction, the laundry (m) is lifted up by the lifter 21b and dropped, so that dirt is removed from the laundry by the chemical interaction between water and detergent.
After an elapse of a predetermined time, the washing machine turns off the motor 15 turns on the drainage pump 42 to drain the used water to the outside of the washing machine. After the drainage of the used water is completed, the washing machine turns off the drainage pump 42.
When the rinsing cycle is inputted, the washing machine turns on and off the feed valve 30, the motor 15 and the drainage valve 42 like in the washing cycle to rinse the laundry.
When the squeezing cycle is inputted, the washing machine operates the motor 15 at a high speed.
As the motor operates at the high speed, the drum 20 rotates too at a high speed. During the rotation of the drum 20, the laundry is closely in contact with an inner surface of the drum 20 to squeeze water from the laundry.
At the time of the high speed operation of the motor 20, the washing machine turns on the drainage pump 42 to drain the used washing water to the outside of the washing machine and turns off the drainage pump 42 when the used washing water is completely drained.
Meanwhile, the washing machine requires less torsion of the drum 20, less damage, and better strength because the drum 20 is agitated in the left and right direction or rotated at the high speed during the washing, rinsing, and squeezing cycles.
The drum 20 may be manufactured as a single plastic injection molding or by coupling a plurality of metal members 21, 22 and 23. Upon considering vibration generated during the rotation of the drum 20 or impact on the tub 10, it is most preferable to manufacture the drum 20 by coupling the metal members 21, 22 and 23.
In other words, it is the trend these days that the drum 20 is configured to include the cylindrical center drum 21, the front drum 22 coupled to a front end of the center drum 21 and having a laundry entrance hole 22a, and a back drum 23 covering the rear surface of the center drum 21.
The center drum 21 has the plurality of holes 21a and a plurality of lifters 21b formed on an inner circumference thereof The laundry entrance hole 22a of the front drum 22 is shaped in a circle. The back drum 23 has a plurality of holes 23a and a spider 23b formed at a rear surface thereof and to which the shaft of the driving motor 15 is connected.
In the related arts, to manufacture the drum 20, the cylindrical center drum is manufactured by rolling a metal plate in a cylindrical form to surface-contact both ends of the rolled metal plate and then welding or bonding the surface-contacting both ends. Then, the cylindrical center drum 21 is coupled with the front drum 22 and the back drum 23 by surface-contacting the cylindrical center drum 21 with the front drum 22 and the back drum 23 and welding the surface-contacting portion.
However, according to the method for manufacturing the drum of the washing machine according to the related art, since the center drum 21 is made in the shape of cylinder by a welding or bonding and the front drum 22 and the back drum 23 are coupled to the center drum by a welding or bonding, the welding portion or the bonding portion may be fractured easily due to a large vibration and more cost is required for the manufacturing of the drum.